<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style type="text/css">
	body>div{
		width: 200px;
		height: 200px;
		background-color: red;
		/*当元素的上边缘和上级元素的上边缘重叠时会出现粘连问题,给上级添加 overflow:hidden解决粘连问题  */
		/*可以解决粘连问题  */
		overflow: hidden;
	}
	div>div{
		width: 100px;
		height: 100px;
		background-color: green;
		margin-left: 30px;
		margin-top: 50px;
		
	}

</style>

</head>
<body>
	<div>
		<div></div>
	</div>
</body>
</html>